Carburetor



June 28, 1938.

A. G. MAHRSTRGM CARBURETOR Filed Feb. 23, 1937 2 Sheets-Sheet 1 June 28,1938. A. G. MAHRSTROM 2,122,348

CARBURETOR Filed Febfzs, 1957 2 Sheets-Sheet 2 lll/l/E/VTOR.

Patented June 28, 1938 UNITED STATES PATENT OFFICE Application February23, 1937, Serial No. 127,254 In Sweden June 11, 1934 3 Claims.

This invention relates to carburetors for internal combustion engines.

The: object of the invention is to provide an efiicient and economicalcarburetor working perfectly under all conditions.

In the drawings:

Figure 1 is a side View of certain parts of the improved carburetor;

Figures 2 and 3 are vertical sections through the carburetor alongplanes perpendicular to each other and showing the air and fuelregulating members in, closed position;

Figure 4 is a section corresponding to Figure 3 of certain parts of thecarburetor showing the air and fuel regulating members in slightly openposition, and

Figure 5 a similar View showing the air and fuel regulating members in amore open position.

The present embodiment of my invention comprises an outer casing Ihaving an axial passageway 2. At its one (upper) end the casing l is:provided with a flange 3 for the connection of the casing to the suctionpipe of an internal combustion engine, and at its opposite (lower) endthe casing I is in a known manner provided with a float chamber 4. Thischamber is provided with a fuel (petrol) inlet 5 and a. float 6 for theregulation of the fuel level. At the end of the carburetor casing Iadjacent the float chamber the casing has a bottom I which at a distancefrom its edge is provided with a socket-shaped portion 8 projecting intothe casing l and perforated by a number of openings 9. Through a centralopening in the bottom I a tube-shaped member 10 passes projecting downin the float chamber 4 and provided at its lower end with a spray nozzleII for the petrol. The upper portion l2 of the member Iii projectscentrally into the casing I and is at its inner end formed with anenlarged head I3, between which and the upper edge of the socket-shapedportion 8 of the bottom I an annular slot or opening I 4 is formed.Within the lower portion of the tube-shaped member In there is centrallyinserted a tube l5 with an outer diameter slightly less than the innerdiameter of said lower portion of the tube-shaped member It. At theupper end of the tube l5 side openings l6 are provided passing to theannular chamber I1 formed between the upper portion of the tubeshapedmember I!) and the socket-shaped portion 8 of the bottom I. To the spacebetween the tubeshaped member It) and thetube I5 there is connected anair supply channel I511 (see Figure 2). This tube I5 is in a knownmanner perforated by a number of air supply openings (not shown in thedrawings) so sized, that fuel flowing from the nozzle II through thetube I5 to the chamber I! will in such a degree be mixed up with airentering through said air supply openings that a rich mixture of fueland air will be produced. 5 The carburetor casing I is interiorly formedat its one end (near the float chamber) with a cylindrical portion I8and, at its opposite end, with another cylindrical portion I9 of asmaller diameter. Between said cylindrical portions the cas- 1 ing I isinte-riorly formed with a conical portion 2!). Within the carburetorcasing I there is slidably mounted a sleeve 2| provided at its one endwith a wider cylindrical portion 22 fitting in the wide cylindricalportion I8 of the casing I and, at its opposite end, with a cylindricalportion 23 of an outer diameter substantially equal to the innerdiameter of the narrow cylindrical portion I9 of the casing I. At itsupper end the sleeve 2| has a bottom 25 with openings or slots 24passing therethrough, which bottom carries a guide ring 26 slidablewithin the cylindrical portion IQ of the casing I. The wide portion 22of the sleeve 2| is near its open free end interiorly so shaped that ona certain distance, counted in the direction of movement of the sleeve,its diameter will successively diminish in the direction against thesaid end, so that the annular opening or slot 28 (see Figure 4) formedbetween the edge of the head I3 and the inner side of the 30 sleeve willsuccessively increase when the sleeve is moved in the direction towardthe bottom I. In a similar way the socket-shaped portion 8 projectingfrom the bottom I is near the bottom I (at 30) so formed that it growswider in the direction toward the bottom 1, so that the annular slot oropening 30a formed between the sleeve 2| and the socket-shaped portion 8will diminish, when the sleeve 2| is moved in the direction toward thebottom I.

The carburetor casing l is provided with a series vof air inlet openings3| distributed around the casing and admitting the outer air to theannular space 32 between the middle portion of the casing I and thesleeve 2|. To a chamber 33 between the casing I and the socket-shapedportion 8 an air inlet opening 34 passes, and in an air inlet tube 35communicating with said opening there is provided an air regulatingvalve 36.

To the sleeve 2| there is fixed a pin 31 (see Figures 1 and 2) the oneend of which projects through a longitudinal slot 38 in the carburetorcasing I. Near said slot a pin 39 is fixed to the casing, and on saidpin there is mounted a twoarmed lever 40 the one fork-shaped arm M ofwhich embraces the projecting end of the pin 31, so that by swinging thelever by means of the other arm 42 in the one direction or the other thesleeve 2| will be moved in the one direction or the other within thecasing The device described works in the followin manner:

In the position shown in Figures 2 and 3, in which the sleeve 2| is mostremote from the bottom 1, the narrow portion 23 of the sleeve 2|entirely or almost entirely closes the narrow, cylindrical portion IQ ofthe carburetor casing I, so that supplementary air from the air inletopenings 3|, is prevented from flowing to the suction pipe of theengine. In this position of the sleeve 2| the edge or circumference ofthe head I3 contacts the inner side of the portion 22 of the sleeve 2|,so that the vacuum in the suction pipe of the engine, which vacuum istransmitted to the interior of the sleeve 2| through the openings 24,can not be transmitted to'the annular chambers l1 and 33. In thisposition of the sleeve 2| (running light position) fuel is admitted tothe interior of the sleeve througha channel 4i! (see Figure 2) passingto the upper side of the head |3 from a channel 44 communicating withthe space between the tube I5 and the tube-shaped member Hi.

When moving the sleeve 2| in the direction to-- ward the bottom 1 therearises between the upper edge of the upper, cylindrical portion 23 ofthe sleeve 2| and the inner side of the carburetor casmg an annularopening or slot (see Figure 4) which increases to a certain limit assaid movement proceeds and through which supplementary air from the airinlet openings 3| is admitted to flow to the suction pipe of the engine.Simultaneously as at said movement of the sleeve 2| said opening or slot45 is formed, an annular opening or slot 28 arises between the head I 3and the inner side of the wide cylindrical portion 22 of the sleeve,which opening or slot in a similar manner increases as the movement ofthe sleeve proceeds. Through said opening or slot 218 the vacuum in theinterior of the sleeve 2| is transmitted to the chamber I1 inside thesocketshaped portion 8 and from there through the openings l6 and thetube l5 to the nozzle The rich .mixture of air and petrol now producedin the tube l5 flows through the openings I6'to the chamber H, where itmeets and gets mixed with supplementary air entering through theopenings 9, further through the opening or slot I4, where the mixturemeets and gets mixed'with further supplementary air coming from the slot30a, and finally through the slot or opening 28 to the interior of thesleeve 2|, from where the mixture escapes through the openings 24 andtogether with supplementary air entering through the slot or opening 45flows to the suction pipe of the engine. I

It is evident that by adapting the shape of the sleeve portion 22 ina'suitable manner in relation to the shape of the portion 20 of thecarburetor casing the mutual relation between the size of the opening orslot 45, which determines the admission of air, and the size of theopening or slot 28, which determines the admission of fuel, may be sochosen that for each position of the sleeve 2| the most economical re--lation between fuel and air' is obtained. The manner in whichsupplementary air is at different points incorporated with the mixtureof fuel tributes to effect an intimate mixture between the air and thefuel.

The outer enlargement 5|] of the socket-shaped portion 8 near the bottomI has for its object to reduce the opening or slot 30a (see Figure 5)when the sleeve 2| is further moved in the direction toward thebottom 1. By this the air admission through said opening will diminishand the vacuum in the chamber I! will increase with the effect that thefuel admission will increase thus effecting a more rich mixture of fueland air flowing to the suction pipe of the engine. To this position thesleeve 2| is brought on such occasions when it is desired to increasethe efficiency of the engine without respect to the economy.

The air inlet valve 36 normally occupies its open position. Whenstarting the engine the valve may occasionally be shut in order toeffect a more rich mixture of fuel and air.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. An improved carburetor for liquid fuel comprising a casing providedat its one end with a bottom and at its other end with an outlet for themixture of air and fuel, a slidable hollow sleeve within said casingadapted to regulate air openings in the walls of the casing and providedwith an axial passage, means for moving said sleeve within said casing,a nozzle outside the casing for atomizing the fuel and producing a richmixture of fuel and air, a channel for conducting said rich mixturethrough said bottom to an annular chamber formed between a memberprojecting centrally from the bottom into the casing and a socket-shapedmember encircling said central member, an enlarged head at the inner endof said central member, an annular passage-way between said head and theinner edge of said socket-shaped member, another annular chamber betweenthe casing and said socket-shaped member, an air inlet passing to thelast-mentioned chamber, and an interiorly conical portion of said sleeveencircling said head, between the circumference of which and saidconical portion there is formed an annular pas-' sage-way the size ofwhich varies with the position of the sleeve, and which passage-wayforms communication between said annular chambers and the interior ofthe sleeve.

2. An'improved carburetor for liquid fuel comprising a casing providedat its one end with a bottom and at its other end with an outlet for themixture of air and fueL a slidable hollow sleeve within said casingadapted to regulate air openings in the walls of the casing and providedwith an axial passage, means for moving said sleeve within said casing,a nozzle outside the casing for atomizing the fuel and producing a richmixture of fuel and air, a channel for conducting said rich mixturethrough said bottom to an annular chamber formed between a memberprojecting centrally from the bottom into the casing and a socket-shapedmember encircling said central member, an enlarged head at the inner endof said central member, an annular passage-way between said head and theinner edge of said socket-shaped member, another annular chamber betweenthe casing and said socket-shaped member, an air inlet passing to thelast-mentioned chamber, means in said inlet for regulating the admissionof air, and an interiorly conical portion of said sleeve encircling saidhead, between the circumference of which and said conical portion thereis formed an annular passage-way the size of which varies with theposition of the sleeve, and which passage-way forms communicationbetween said annular chambers and the interior of the sleeve.

3. An improved carburetor for liquid fuel comprising a casing providedat its one end with a bottom and at its other end with an outlet for themixture of air and fuel, a slidable hollow sleeve within said casingadapted to regulate air openings in the walls of the casing and providedwith an axial passage, means for moving said sleeve in said casing, anozzle outside the casing for atomizing the fuel and producing a richmixture of fuel and air, a channel for conducting said rich mixturethrough said bottom to an annular chamber formed between a memberprojecting centrally from the bottom into the casing and a socket-shapedmember encircling said central member, an enlarged head at the inner endof said central member, an annular passage-Way between said head and theinner edge of said socketshaped member, another annular chamber betweenthe casing and said socket-shaped member, an air inlet passing to thelast mentioned chamber, an interiorly conical portion of said sleeveencircling said head, between the circumference of which and saidconical portion there is formed an annular passage-way the size of whichvaries with the position of the sleeve, and which passage-Way formscommunication between said annular chambers and the interior of thesleeve, and channels passing through said socket-shaped member betweensaid annular chambers.

ANTON GEORG MAHRsTRoM.

